1. Field of the Invention
The invention relates to a composite panel comprising a core and at least one outer sheet which is adhesively bonded to the core, said composite panel being shape-formed creating at least one radius of bending in the outer layer.
2. Background Art
Composite panels that have a core of plastic and metallic outer layers and are shaped by bending are known from EP-B-0423073 and DE-A-3831363. The bending operation is performed after notching or embossing the outer sheet lying on the inner side of the bend. Depending on the degree of bending the radii of bending are greater or smaller along the notched or embossed line. Small radii may lead to separation of the adhesive provided between core and outer layers, which has a negative effect especially on corrosion resistance, firmness and fatigue strength.
As a rule curved composite panels are produced using expensive positive and negative dies and complicated bonding methods. As special dies have to be made for each shape, this method of manufacture involves high manufacturing costs. If the bending radius is small, it may be necessary to machine away the inner face of the outer layer, which is closed off again on bending. As this causes local disruption of the outer layer, there is a very large loss of strength in the region where such panels have been bent; this loss of strength has to be restored by appropriate means such as e.g. strengthening of the corners.